A planetary, H-group pebble in the Barwell, L6, unshocked chondritic meteorite

One stone of the Barwell (L6) shower contains an igneous inclusion with the oxygen isotopic signature of H-group chondrites. The inclusion is composed dominantly of olivine with a composition, Fo 75.5, identical with that of its host; other phases are only partially equilibrated with the host. The inclusion has a fractionated rare earth element pattern showing depletion in the heavy rare earth elements and a positive Eu anomaly; it is depleted in siderophile elements. Inclusion and host have Ar Ar ages (4.44 and 4.51 Ga, respectively) and 129Xe r/I ratios identical within experimental error. We conclude that melting occurred very early on an H-group chondritic body. Two objects from a single meteorite have different oxygen isotopic ratios but identical 129Xe r/ 127I ratios, which may indicate that the I Xe systematics reflect chronological differences in closure to Xe rather than isotopically heterogeneous iodine. The inclusion and its host cooled to Xe closure temperature contemporaneously with chondrules from unequilibrated ordinary chondrites.